Westholme Clinic, in Clive Avenue, Goring, and South Coast Care Agency, based in South Street, Tarring, were separately given the lowest rating by the Care Quality Commission (CQC).
Both pledged to improve when they are revisited.
A spokesman for Westholme said: “The CQC commented during their visit how professional and passionately the staff were delivering care to the clients. We do not agree with this rating.
“I am sure as soon as they re-visit the home we will be back to the rating which we had for the last 20 years.”
The home was inspected in February, following complaints from relatives and the public.
They found people’s safety ‘compromised’, unsafe management of medicines and people at serious risk of harm, due to inadequate management of those confined to their beds.
Inspectors found unsecured medicine bags in the hall, unsealed sharps bins and overflowing medical containers in the clinical room and inadequate care plans.
Staff were, however, judged to be friendly and some relatives told inspectors it was a ‘caring’ home.
The manager has since stepped down.
The agency, meanwhile, assured the Herald it had ‘addressed all areas’ highlighted by the report.
The CQC acknowledged it had improved safeguarding since an earlier visit but had failed to make strides in other areas.
Care plans did not reflect individual needs, medicines were not managed safely and recruitment processes were not followed. One person was ‘at risk of overdose’ if they took their own medicines, yet their care plan detailed medicines being left on a chair in their lounge.
The inspectors also spoke to residents, one of which commented they were ‘very satisfied’ with the service.
Director Karen Jacobs said: “We have taken on board all feedback and we work continuously to improve and better our service for our customers.
“We have invested time to enhance the development and skill set of our care staff and provided further training where needed.”
Read the full reports at www.cqc.org.uk